A wily cat is a special variant of a pet cat, which players gain access to by completing the Ratcatchersquest. After completion, players can speak to Felkrash to have her train their overgrown cat into a wily cat. (WARNING: After training your overgrown cat to be a wily cat, you will start from zero for the number of rats caught for the cat training medal.) Wily cats are the best hunters of any cat, with a success rate of 70%. In addition, they can also catch kalphite larvae and butterflies, though this yields no experience in Hunter for the player. Wily cats do not require food of any kind.

Players are only allowed to have one wily or lazy cat at a time, in addition to one kitten or adult cat, and as many overgrown cats as they wish. You may have multiple wily cats if you first store your existing wily cat in your menagerie before training another.

While wily cats do not need attention like kittens do, the amount of attention they have received influences the dialogue when the wily cat is spoken to.

When asked how it is doing, an angry cat will hiss and complain that it hasn't been petted enough.

Once it has been petted enough, it will say that it is content, but wants to hunt more rats.

Once that need is satisfied, it will purr and say it is happy, but that the player shouldn't take this as a sign to start neglecting it again.

There is no benefit to a fully content wily cat.

Wily and lazy cats can be named by speaking with Felkrash. The name can be a combination of any six letters or spaces, but no numbers. The name input will appear in the follower detail window instead of the follower name. Note that the name will be used in the RuneScape interface for every cat the player has, even kittens, adult cats, and overgrown cats.

After a random amount of time, usually under an hour, regardless of the amount of interactions performed, a wily cat will become a lazy cat. Lazy cats can only catch rats, and have around a 41% success rate.

They can be trained back into wily cats by performing a random amount of interactions with them. The easiest way to accomplish this is to use the mouse toy, which players can equip as a weapon, and then right click and select "play" repeatedly. Players can no longer have two mice, however, the toy mouse now activates when equipping the item. Rapidly switch between this item and another weapon creates the same effect as two mice. Other options are to play with the cat with a ball of wool, sending it to chase rats, and stroking it.

It generally takes about 25 rats to transform a lazy cat of any type back into a wily cat, which can easily exceed the game play length of having a wily cat.